Turbulators formed of heat conductive metal have been incorporated interiorly within tubular pipes or conduits to facilitate heat exchange between the fluid flowing internally within the pipe or conduit and a further fluid external of that pipe or conduit.
Such turbulators are evidenced by U.S. Pat. Nos. 1,056,373, 2,161,887, 2,591,398, 4,106,558,. 4,179,222, 4,296,779, 4,577,681, and by French Pat. Nos. 964,415 and 1,501,967 and British Pat. No. 398,154.
Turbulators have been formed of strip metal. cylindrical metal tubes, or the like which have been given bends, or flats at longitudinally spaced positions and such turbulators may include partially struck out portions which project into the flow stream and which tend to magnify the turbulence of the fluid flowing under pressure through the interior of the conduit or pipe to thereby enhance heat transfer between the fluid passing through the conduit or pipe, and the exterior surface of the conduit or pipe which is in physical contact with a second fluid.
U.S. Pat. No. 1,056,373, for instance has a elongated metal strip of a width slightly narrower than the internal diameter of the external pipe or conduit through which the turbulator strip extends. The strip is twisted about its axis. Further, tabs or elongated fingers are partially struck out of the strip at periodic longitudinally spaced positions along the length of the twisted metal strip.
In U.S. Pat. No. 2,161,887, partially struck out tabs are at the apices of a folded metal strip which extends in serpentine fashion through the interior of a heat exchange tube. The tabs tend to deflect the fluid passing through the interior of the tube against the exterior wall.
U.S. Pat. No. 4,106,558 further evidences the partial strike out of a piece of a sheet metal strip, forming a deflector tab for the fluid passing through the tube bearing such turbulator.
French Pat. No. 1,501,967 shows a turbulator within an outer cylindrical pipe or conduit, the turbulator being formed of a tube which is flattened to provide flats at circumferentially alternating positions and with longitudinally adjacent flats being at right angles to each other.
French Pat. No. 964,415 shows a turbulator formed by first taking a strip of material folding it in half, crimping it at certain longitudinal locations to form bulbous portions which taper and then twisting the strip 180.degree., between the bulbous portions.
British Pat. No. 398,154 teaches near flattening of a tube and the formation of triangular shaped transition or connecting portions for the narrowed segments of the tube defined by the flattening process.
The balance of the patents not discussed specifically within the group listed above, teach the adjoining of multiple strips of metal into an assembly which extend the length of pipe and which assembly is positioned interiorly thereof to effect a transition in the movement of fluid longitudinally within the pipe and to effect a turbulence to the fluid flowing therein thereby tending to enhance heat exchange between the fluid internally of the pipe and one externally.
While such turbulators have functioned adequately, even minor improvements in heat exchange efficiency of the heat exchangers employing turbulators amount to a significant improvement where there is little margin for error in achieving the desired heat exchange between a fluid captured internally within the heat exchange conduit and a second fluid external thereto.
This is particularly true in the area of oil coolers for diesel engine driven trucks and the like where, the ability of the engine oil to effectively lubricate the moving parts of an internal combustion engine is delatoriously affected by the operating temperature of the engine.
The improved turbulator of the present invention is particularly useful within such oil cooler heat exchanger in which the oil flows under pressure through a cylindrical metal pipe or conduit, and is cooled by an ambient air stream flowing over the external surface of the conduit.